1. Field of the Invention
The present invention relates to movable body apparatuses, exposure apparatus, exposure methods, and device manufacturing methods, and more particularly, to a movable body apparatus including a movable body which holds an object and is movable in a direction parallel to a first axis in a two-dimensional plane, an exposure apparatus which is equipped with the movable body apparatus and is used in a lithography process to produce electronic devices (microdevices) such as a semiconductor device, a liquid crystal display devices and the like and an exposure method of the exposure apparatus, and a device manufacturing method which uses the exposure apparatus or the exposure method to manufacture an electronic device (microdevice).
2. Description of the Background Art
Conventionally, in a lithography process for manufacturing electronic devices (microdevices) such as a semiconductor device, a liquid crystal display devices and the like, a projection exposure apparatus is mainly used that reduces and transfers a pattern formed on a mask or a reticle (hereinafter generally referred to as a “reticle”) onto an object subject to exposure (hereinafter generally referred to as a “wafer”) such as a wafer or a glass plate and the like, via a projection optical system. As the projection exposure apparatus, a step-and-repeat type reduction projection exposure apparatus (a so-called stepper), and a step-and-scan type projection exposure apparatus (a so-called scanning stepper) are used in relatively large numbers.
In recent years, a scanning type exposure apparatus such as a scanning stepper which synchronously moves in a predetermined scanning direction (scan direction) with respect to illumination light, and transfers a pattern formed on a reticle on a wafer via an optical system has become mainstream.
In the scanning type exposure apparatus such as a scanning stepper, a drive device to drive the reticle is also necessary for the reticle side, as well as the wafer side. In the recent scanning type exposure apparatus, as the driver of the reticle side, a reticle stage device is employed which drives a reticle stage supported by levitation on a reticle surface plate by air bearings and the like using, for example, a linear motor in the scanning direction in a predetermined stroke range, as well as finely drive the reticle stage in the scanning direction and a direction besides the scanning direction.
However, because scanning steppers are used when performing mass production of microdevices, improvement of throughput is inevitably requested. Therefore, in recent reticle stage devices, a reticle stage device is used in which an upper and lower pair of linear motors is provided for drive in the scanning direction on both sides of the reticle stage in a direction besides the scanning direction, and by these two pair of linear motors, the reticle stage is driven in the scanning direction with a neutral surface including the center of gravity of the reticle stage serving as a drive plane (refer to, for example, Kokai (Japanese Patent Unexamined Application Publication) No. 2008-166614). In the reticle stage device disclosed in Kokai (Japanese Patent Unexamined Application Publication) No. 2000-166614, in between the pair of linear motors on one side in the direction besides the scanning direction, a linear motor used for drive in the direction besides the scanning direction is provided, and an extended portion is provided between the pair of linear motors on one side in the direction besides the scanning direction, and a mirror used by the interferometer use was fixed to the extended portion.
In the reticle stage device disclosed in Kokai (Japanese Patent Unexamined Application Publication) No. 2008-166614, high acceleration and speedup can be realized, and by being driven in the center of gravity, generation of pitching moment can be effectively suppressed.
However, in the exposure apparatus, requirements are pressing for further improvement in throughput, and to achieve such requirements, in the scanning type exposure apparatus, a much higher acceleration of the reticle stage needs to be realized. Furthermore, in the exposure apparatus, it is required that (the image of) the pattern of a reticle is transferred (formed) on a substrate such as a wafer faithfully, without the image being blurred.
However, the device rule (practical minimum line width) of semiconductor devices and the like is becoming finer, and accompanying this, deformation of a patterned surface which occurs due to deformation of the reticle caused by its own weight and the like brings about defocus, distortion of the pattern image and the like, which in turn are becoming an obstacle when a desired exposure accuracy (including overlay accuracy) is to be achieved.
Further, in the projection exposure apparatus, the exposure wavelength has been shifted more to the short wavelength side so as to achieve high resolution in correspondence with finer integrated circuits. Currently, the mainstream of the wavelength is 248 nm of the KrF excimer laser, or 193 nm of an ArF excimer laser which belongs to the vacuum ultraviolet region having a shorter wavelength than the 248 nm. However, in ArF lithography, haze (fog) defect of the reticle has come to be a serious influence on the productivity and the production cost, and is becoming a major problem.
In the exposure apparatus, as a method to realize effective measures to comprehensively suppress the haze formation on the reticle, surrounding the space around the reticle and purging the space with the purge gas such as clean dry air or other purge gases so as to remove moisture, for example, to no more than a ppm order, can be performed.
And because the moisture is removed to no more than a ppm order, the inside of the purge space turns into a state where static electricity can very easily occur. The reticle is a representative of an object which is loaded and unloaded many times in the exposure apparatus. Therefore, with the reticle, the stage on which the reticle is mounted, and a carrier hand of the reticle and the like, a floating state occurs where there is no discharge for the electrostatic charges which are generated by being electrically insulated. By the electrostatic charge that is generated, the pattern on the reticle is vulnerable to damage by a so-called ESD (Electrostatic Discharge). It is said that the withstand pressure of a silicon nitride film is 0.1 V/A in general, and recent oxide films are thinned to several A. Therefore, because pattern destruction may occur even in a voltage of 1V or less, sufficient countermeasures against static electricity are necessary. Further, for example, the electrostatic charge generated on the reticle attracts undesirable substances which are referred to as a contamination, and such contamination becomes an interfering substance upon exposure.
As described above, in the exposure apparatus using ultraviolet rays, especially the ArF excimer laser beam, because water absorption in the wavelength of the ArF excimer laser beam is strong, water concentration is reduced and the concentration is strictly controlled in order to obtain enough transmittance, which can easily damage the pattern on the reticle by the so-called ESD (Electrostatic Discharge) due to the electrostatic charge which has been generated. On the other hand, because the exposure apparatus is used to perform mass production of semiconductor devices and the like, a high throughput is naturally required.